In recent years, with developments of science and technology, portable electronic products are rising gradually, and especially the portable electronic product with a camera function is more popular with people. More and more kinds of image acquisition devices are developed gradually, and a camera lens which may be applied to the image acquisition devices in various imaging fields is more popular in the market. A photosensitive element in a common optical system generally includes nothing more than a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS). With progresses of a semiconductor process technology, the optical system trends to have a higher resolution, a pixel size of the photosensitive element becomes smaller and smaller, and a requirement for imaging quality of the matched optical system becomes higher and higher.